Throughout the 1930s, Fox Studios made a ton of very successful Charlie Chan films. It isn't surprising that this led to knock-off characters like Mr. Moto (also from Fox) and Mr. Wong (from poverty row giant, Monogram Studios). Frankly, while the Moto and Wong films are pleasant enough B-movies, they are too similar to the Chan films but lack their charm and wit. In the case of Wong and Chan the similarity was even greater as both were of Chinese descent, traveled the world and were "do-gooders" who often helped the helpless when conventional police work failed.
In the early 1940s after Monogram completed six not particularly distinguished films AND Fox decided to discontinue the Chan series, an opportunity arose for Monogram to bring Sidney Toler to the studio and make their own Chan films. As a result, Wong was expendable and since four years had passed since the last film in this series, the studio heads decided they wanted no more Wongs. Besides, if they had Chan AND Wong, the resulting films would be like having two Wongs--and that's just not right.
MR. WONG, DETECTIVE is the first Wong film and there's nothing particularly wong, I mean WRONG about the film. It was entertaining and had a nice mystery. However, it's also an awful lot like several other Monogram films--and is most like their next Wong film, THE MYSTERY OF MR. WONG. It's also a lot like the Chan films, MURDER OVER NEW YORK, THE JADE MASK and DOCKS OF NEW ORLEANS. In other words, many plot elements were repeated and after a while the films started to be indistinguishable from each other--something that was NOT a problem with the Fox films.
Overall, it's worth seeing and is possibly the best film of the series--though this isn't saying a lot.